This tool is a collection of Leader Guides that fully support 8 or more 3-hour workshop sessions. The Guides feature rich mathematical tasks, student work, and classroom video recordings. The series is designed around three themes: Understanding Student Understanding; Using Assessment to Support Teaching and Learning; and Scoring What We Value. It builds on a practice of professional development that focuses on teacher learning and shifts the curriculum and discourse of professional development away from simply giving teachers things to do in their classroom toward providing support for more reflective approaches to assessment and instruction.